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add support for timestamps to datatuple comparator

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git-svn-id: svn+ssh://svn.corp.yahoo.com/yahoo/yrl/labs/pnuts/code/logstore@2446 8dad8b1f-cf64-0410-95b6-bcf113ffbcfe
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sears 2011-04-22 17:38:18 +00:00
parent 65efc768a4
commit ab9cfd1443
1 changed files with 38 additions and 16 deletions
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38
datatuple.h
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@ -53,14 +53,34 @@ public:
}
/**
* This function handles ASCII and UTF-8 correctly, as well as 64-bit
* and shorter integers encoded with the most significant byte first.
*
* It also handles a special tuple encoding, where multiple utf-8 strings
* are concatenated with \254, and \255 is used as a high key. \254 and
* \255 never occur in valid UTF-8 strings. (However, this encoding
* tie-breaks by placing substrings *later* in the sort order, which
* is non-standard.)
*
* If a key is greater than 64-bits long, then this function checks to see
* if the 9th to last byte is zero (null bytes are disallowed by both ASCII
* and UTF-8. If so, it discards everything after the null. This allows
* us to pack a 64-bit timestamp into the end of the key.
*
*
* return -1 if k1 < k2
* 0 if k1 == k2
* 1 of k1 > k2
**/
*/
static int compare(const byte* k1,size_t k1l, const byte* k2, size_t k2l) {
// This function handles ASCII and UTF-8 correctly.
// It also handles a Sherpa LSM-Tree specific encoding, where multiple utf-8 strings
// are concatenated with \254., and the \254 is replaced with a \255 for 'max value in range'.
const size_t ts_sz = sizeof(int64_t)+1;
if(k1l > ts_sz && ! k1[k1l-ts_sz]) {
k1l -= ts_sz;
}
if(k2l > ts_sz && ! k2[k2l-ts_sz]) {
k2l -= ts_sz;
}
size_t min_l = k1l < k2l ? k1l : k2l;
@ -69,11 +89,13 @@ public:
if(k1l < k2l) return -1;
if(k1l == k2l) return 0;
return 1;
}
//for testing with char* ending with \0
/*assert(strlen((char*)k1) == k1l - 1);
assert(strlen((char*)k2) == k2l - 1);
return strcmp((char*)k1,(char*)k2); */
uint64_t timestamp() {
const size_t ts_sz = sizeof(uint64_t)+1;
size_t al = keylen();
if(al <= ts_sz || key()[al-ts_sz]!=0) { return (uint64_t)-1; }
return *(uint64_t*)(key()+1+al-ts_sz);
}
static int compare_obj(const datatuple * a, const datatuple* b) {